The ventromedial portion of the hypothalamus (satiety center) is an essential link in a regulatory system which adjusts food intake to energy output so that the weight of the mature animal remains fairly constant. The critical role of the satiety center in this system is demonstrated by the gross increase in voluntary food intake, and the resultant obesity, which follow ablation of the center. Our broad objectives are to elucidate the physiology of the center and the biochemical properties underlying its function. It may be reasonably anticipated that understanding of the factors which influence satiety center activity will be useful in the management of the clinically important problem of obesity. We have found that the center responds to insulin, glucocorticoids and inhibitors of glucose utilization and that specific glucoreceptor cells are present in the center. Changes in feeding behavior are correlated with changes in the activity of the center produced by these agents. The recent demonstration that phlorizen, insulin, gold thioglucose and glucose preferentially bind to one specific cell type in the satiety center provides additional support for the presence of special glucoreceptor cells in this region of the hypothalamus. We propose to study the anatomical characteristics of these cells and to determine the biochemical properties underlying their function in the control of feeding behavior.